Applying for and getting approved for veterans disability benefits can be a long and difficult process. Veteran's benefits are paid to a veteran because of injuries or diseases that are "service connected," which means they happened while on active duty, or were made worse by military service. A service-connected disability can include any problem incurred while you were in service, even if you didn't receive treatment while in there. This applies to injuries that happened during combat, or even while on leave.
This video discusses the basic issues involved in applying for and winning veterans disability benefits.